My re-install deleted ALL files that started with letters E-Z, wtf???

Hi, I own a music program called Reason, and the other day it wouldn't open because of a "read problem." Now, I re-installed the program and after I did this, something very odd happened. The songs that I had previously produced and saved in a certain folder (Reason/songs folder) which began with the letters A-D were still in the folder, but every song that started with letters E-Z were no longer in the folder. I checked to see if they were hidden files, nothing came up. I had backed up my hard-drive a few months back, so I went to copy the songs (E-Z)from my back-up, back into my original Reason/songs folder, and that's when ANOTHER odd thing happened. It asked me if I wanted to overwrite the files, the E-Z files that aren't showing up in the folder anymore! I tried copying numerous songs in the E-Z category from my backup source, and the destination folder (Reason/songs) kept saying that I would be overwriting these files that are NOWHERE to be found. This must mean that the files are still in my hard drive, but for some reason won't reveal themselves. Does ANYBODY have any idea how to retrieve these files or bring them back to life, since they are now ghosts floating around somewhere in my folder? Phewww that was a lot of typing : )